Description (Taken from the Investigator's Abstract) The objectives of this core facility are to support three of the proposed projects in this study: Lovelace Institute Rat studies, the Sheep and Rat Animal Model Studies, and the Biomarker and Epidemiology Studies. This facility will provide a variety of services including immunohistochemical staining for toxins, characterization of cellular elements on swabs and scraping and review of histological slides. The immunohistochemistry Core Facility is located within the Division of Comparative Pathology in the Papanicolaou Cancer Research Building. The Division has over 6,000 square feet of laboratory, administrative and office space. There are four full time faculty members and an administrative and support staff of 10 individuals. The laboratories are fully equipped to perform the proposed studies except for the specialized microscope for morphometry, which is included in the budget. The complete histopathology laboratory is available including a Fischer Histomatic model 166MP Tissue Processor, a Shandon Embedding station, two Leitz model 1512 Microtomes, an AO Cryostat, and complete equipment for routine, special stains, and immunohistochemistry. In addition, basic research equipment such as centrifuges (refrigerated/non- refrigerated, and high speed), light microscopes, refrigerators, freezers, autoclaves, C02 incubators, biological safety cabinets, microfuges, ELISA readers, a gamma counter, fume hoods, water baths, fluorescent microscopes, and a walk-in cold room are also available. The shared department resource area also includes a fully equipped laboratory for PCR analysis. Office space is available for participants in this facility that includes their own personal computers with Internet access, multiple programs including Word and Excel, and several data analysis programs.